Arthur bessey smith



A. B. SMITH.

VOICE CURRENT TELEPHONE REPEATER.

APPLICATION FILED JUNE 6. 1918.

1,412,067, I Patented Apr. 11, 1922.

tJhliTEl-Q ARTHUR BESSEY SMITH, OF EVANSIOIT, ILLINOI.S. ASSIGNOR TO AUTOMATIC ELEC- TRIO COMPANY. OF CHICAGO. ILLINOIS, A CORPORATION OF ILLINOIS.

VOICE CURRENT TELEPHONE R-EIEATER.

TEAEZOGZ.

Application filed June 6,

T 0 (ZZZ whom it may concern:

Be it known that I, ARTHUR Bnssnr SIJITIFI, citizen of the United States of America, and resident of livanston, in the county oi Cook and State of Illinois, have invented certain new andL useful Improve ments in Voice-Current Telephone Repeaters, of which the following is a specification.

My invention relates in general to voice currentrepeaters t'or use in telephone systems, and more specifically to a two way .amplifier or repeater. which is adapted for use in amplifying voice currents and repeating the same in either direction over a long distance trunk line.

Among the objects of my invention are to provide such a device having efiicient devices for switching a single amplifier to repeat currents in either direction; to so arrange saidswitching or orienting devices that the amount of energy diverted to said devices for operating the same is ver sn all, therefore causing a minimum transmission loss; and to provide novel circuits and mechanism for accomplishing the ahovc objects.

Certain repeaters oi this character have becn designed in the past, some having certain complicated devices or circuit arrangements for preventing singing action between a pair of amplifiers which were both normally in the circuit together, and other having switching devices for cutting out one amplifier and cutting in another by certain devices. It is thought however, that the devices illustrated and explained in my specification and drawings constitute a very great advance in the art and provide a r ipoator which will meet all the rigid requirements for the service it is designed to give in an improved and more efficient manner tiaz any device so far designed.

Having pointed out the features and the main objects of my invention I will endeavor to describe more in detail the operation of the same by referring to the accompanying drawings in which I have shown a schematic diagram of the circuits of one embodiment of my invention.

I have shown only a portion of a long distance trunk line which it will be understood may connect any two distant points and over which it is desired to improve the transmis sion by inserting a device which will receive Specification of Letters Patent.

' rent is first Patented Apr. 11, 1922.

1918. Serial No. 238,441.

weakened voice currents from one end of said trunk line. amplify or increase the amplitude of the voice current waves and repeat the same to the other end. In order to adapt the amplifier to be switched over for repeating in either direction I have provided certain sensitive devices which respond to voice currents from either end of the trunk line to so arrange the amplifying 'epeater in the circuit. that voice currents from the line over which conversational curdelivered will be received in the receiving device of the amplifier and re pcated to the other end. After conversation is discontinued from this end of the trunk line the repeater remains switched as last used until the party on the other end hegins to speak, at which time the said repeater will be switched over to repeat in the opposite direction. The switching devices are operated mainly by a portion of the amplified energy, only a small portion of the weak incoming energy being first used to start the switching.

In the drawings A is one end of a trunk line which passes through contacts of a switching relay 6 to the amplifier having a receiving device 2, a transmitter 3, which repeats voice currents through the medium of a local circuit including a'battery 5, and an induction coil lhaving a primary and a secondary winding. The trunk line A may be switched by the relay 6 into circuit with the receiving device 2 or the secondarywind' ing of the induction coil. The trunk line B from the opposite end also passes through contacts of a switching .device 7 which may connect said trunk line to the receiver 2 or the secondary of coil 4. It will be under stood that the amplifier here represented as a receiver and a transmitter may as well be any known type of amplifier known in the art which receives weak talking current and repeats the same in an amplifier form.

in hridge of the secondary winding of the induction coil l is a high resistance bridge having a relay 8 included therein. This relay is so adjusted as to respond to only repeated or amplified currents, and will not operate with weak incoming current which comes direct from either end oi. the trunk line. The relay 9 is similar to relay 8 except that it is connected in series with the induction coil 4 and is arranged to operate with weak incoming currents from either of relay may be used. 9 each have a stiff armature which responds to the fluctuations of the alternating current trunk line A or B. If it is desired to make this relay G more sensitive to weak incoming current, the relay may be connectedas shown in the diagram at the upper part of the drawing, that is, the weak currents may first pass through the receiving device 31 of a step-up amplifier, and the relay 9 con nected in circuit with the secondary winding of the induction coil 33 of said amplifier sothat in this case relay 9 will receive stronger current than if connected directly in series I with the line. The amplifier here shown maybe of any approved type.

These relays 8 and 9 may be of that type of relay shown in U. S. Letters Patent $11,221,299 granted A ril 3, 1917 to C. J. Erickson, although any other similar type These relays 8 and and have also a spring having a weight I thereon. Now as the stilt armature vibrates 7 attached to its central point to overbalance it and is so arranged that it will stay in whichever position into which it IS drawn by either the coil 10 or 11.

I will now explain the. detailed operation of the circuits and devices when a party on line ,A who has been connected in any manner to the subscriber on line B starts to converse with said othersubscriber. The circuits asshown are already in position so that A may talk to B without any switching operation being necessary as relay 6 is now energized and relay 7 is deenergized. Therefore as current from line A. passes through the front contacts of relay 6 and through the receiving device 2, these currents will be amplified by the transmitter 3 and a similar voice current of greater amplituoe will .ileenergized position. This relay 7 be induced in the secondary oi the induction coil 1. These amplified currents will now pass through. the relay 9, back contacts of relay 7, and line B, and also in multiple with the line B will pass through the bridged relay 8. Relays 8 and 9 will therefore operate simultaneously. Relay 8 upon opening the springs 19 and 20 removes the ground from the circuit of both windings ot the switching relay 7 to maintain the same in I 7 is wound differentially so that it attracts its armatures only when the circuit of one winding is opened and the other closed. The circuits opened by the springs 19 and 20 extend from ground through said springs, springs 2st and springs 21 and 22, relay 10, springs 19, and upper winding of relay '7 to battery, and from ground through springs 19 and 20, springs 28 and 30, and lower winding of relay 7 to battery. The springs 21 and 22 at this time open one point in a circuit from ground through springs 19 and 20, springs 24 and 23, springs 21 and 22, relay l0, springs 19, and upper winding of relay 7 to battery. It will be seen that relay 9 has no effect at this time as relay 8 has opened the circuits of both windings of said.relay 7. The conversation may therefore be carried on over the heavy conductors as shown and relay 8 will continue to operate as long as a party on line A continues to speak. The bridge across the secondary oi coil 4 consisting of the relay 8 which is in series, with. resistance 12 is of such high resistance that very little of the voice current is consumed thereby and the transmission is only slightly affected.

Now when the party on line A stops talking and the subscriber at B starts to talk while the apparatus stands as shown, voice currents from said line B will pass through the spring 16 and its back contact, secondary of induction coil 4, windings of relay 9, back contact of spring 17, and to the other side of line B. The relay 8 is in bridge of the secondary winding of coil 4, but having a high resistance 12 included in the bridge, does not operate nor divert much of the current from this circuit but relay 9 which is in series with this circuit is sensitive to weak currents and operates at this time to open the springs 21 and 22. The opening of the springs 21 and 22 opens the circuit leading from ground through springs 19 and 20, springs 24 and 23, springs 21 and 22, relay 1O, springs 19, and upper winding of relay 7 to battery. The relay 7 immediately energizes by the action of its lower winding which is closed to ground through springs 30, 28, 20 and 19, and oper-' ates to close the springs 18 first and to then disconnect the line B from the induction coil a and connect it instead to the receiv ing device 2. The closure of springs 18 closes a circuit from ground through springs 19 and 20, springs 24 and 23. relay 11, springs 18, and upper winding of relay 6 to battery. As thelo wer winding of said relay 6 is already energized through springs 26 and 25, and said relay being differentially wound, then relay 6 will immediately fall back to open. the springs 19 and switch the line A from the receiving device 2 to the induction coil 4. Relay 11 also energized over the above circuit to operate the armature 13 which substitutes the ground on spring 29 for the ground from springs 19 and 20 in the circuit of the lower winding of relay 7 to maintain the relay 7 energized without regard to the operation of relay 8: substitutes the ground from springs 19 and for the ground on spring in the circuit of the lower winding of relay 6: closes one point at springs 27 and 28 in the circuit of the upper winding of relay 6 and relay 11 extending from ground through springs 19 and '20. springs 27 and 2S, springs 21 and 22. relay 1.1. springs 18, and winding of relay 6; and opens the springs 23 and 2% which were in said circuit. It will be understood that the armature 13 has a long stroke and operates more slowly than relays 6 and 7 so that by the time armature 13 reaches its position tilted to the left, the talkingcurrent from line B will have passed through the amplifier and energized the relay 8 which upon opening the springs 19 and 20 prevents any further change in the circuits by the operation of relay 9. Relay 8 upon thus operating opens simultaneously the circuits of both windings of relay 6 which therefore remains deenergized. It will be seen that although relay 9 also operates to open one winding of relay 6 the operation of relay 8 renders this operation ineffective at this time.

The purpose of relays 10 and 11 is therefore to switch the springs 21 and i2 first in circuit with one winding of relay 7 and then in circuit with a winding of relay 6, but the relay 8 while operating prevents said springs from operating the associated relay. As long as the party on line B talks therefore,

the circuit will remain the same. relay 7 holding energized through its lower winding and relay 6 remaining deenergized either because the circuit of both windings are open at springs 19 and 20 or are both closed at said springs. It will also be seen that even if the subscriber at B ceases talking the circuits will remain switched in the same manner until the subscriber at A begins to talk. This circuit is more practical than certain other circuits which have been designed in the past in which it is necessary to keep talking to hold the circuits connected for repeating one Way, while in my arrangement only a small part of the weak incoming current is used up at the instant when conversation begins and after that no change is required until the other party begins to talk.

Now, after B ceases conversation the party on line may again desire to talk to the subscriber on line B in which case currents from lire A will pas, through spring 14- and its h 1 k contact, through the secondary winding i1l(l1l(?i'i()l'l coil l. relay 9. spring 15 and its hack contact. and to the other side of line A. nelay S is in a high resistance bridge of the induction coil l but does not energize. Relay 9 however, operates to open the springs ill and 22 which are now in the circuit of the upper winning of relay 6 extending from ound through springs; 19 and 20, springs 2! and 28, springs 2t and 22, springs 18,and

upper winding of relay 6 to battery. Relay 6 energizes at this time to close the springs 19 in the circuit of the upper winding of relay 7 and to switch the line A from the induction coil to the receiving device 2. The circuit closed for the upper winding oi? relay 7 includes at thi time the winding of relay 10. which now energizes to draw the armature 13 over to its right hand posit-ion. As soon as the talking current reaches device 2 and therefore the induction coil l. the relay 8 is operated to open the springs 19 and 20 to prevent any further change in the circuit and after this the circuits will again stand as shown in the drawing until the subscriber s. ceases talking and B begins to talk.

It will be seen therefore that I have )IO- vided a very etlicient and practical method of switching an amplifier into position to repeat currents in either direction. This device always stands as last used, so that the first part of the first wave of current sent in will operate to reverse the circuits and should a talking subscriber pause for any length of time the circuits remain oriented in the proper direction to repeat continued conversation from that line without further switching until the other subscriber begins to talk.

Having fully described and ascertained my invention what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims:

\Vhat I claim is 1. In a telephone system, a pair of lines joined by a voice currentrepeater, whereby weak talking currents may be received from one of said lines and repeated in amplified form to the other line, switching devices for connecting said repeater to repeat to either of said lines. a sensitive relay for controlling said switching device, means for bringing said relay under the control of either line, and means for rendering said sensitive relay ineifective 2 In a telephone system, a pair of lines joined by a voice current repeater. whereby weak talking currents may be received from one of said lines and repeated in amplified form to the other lines, switching devices for connecting said repeater to repeat to either of said lines, a sensitive relay for controlling said switching device, means for bringing said relay under the control of either line, and another sensitive relay for rendering said first sensitive relay ineffective.

In a telephone system, a pair of lines joined by a voice current repeater, whereby weak talking currents may be received from one of said lines and repeated in amplified form to the other line, switching devices for connecting said repeater to repeat to either of said lines, a sensitive relay for controlling said switching device, and means for bring "ng said relay under the control of either no, said relay operated by either weak or amplified currents.

4. In a telephone system, a pair of lines joined by a voice current repeater, whereby weak talking currents may be received from one of said lines and repeated inamplified form to the other line, switching devices for connecting said repeater to repeat to either of said lines, a sensitive relay for con trolling said switching device, means for bringing said relay under the control of either line, said relay operated by either weak or amplified currents, and means for rendering said sensitive relay ineffective when operated by amplified currents.

5. In a telephone system, a pair of lines joined by a voice current repeater, whereby weak talking currents may be received from one of said lines and repeated in amplified form to the other lines, switching devices for connecting said repeater to repeat to either of said lines, a sensitive relay for con trolling said switching device, means for bringing said relay under the control of either line, and another sensitive relay for rendering said first sensitive relay ineffective, said'first relay operated by either weak or amplified currents.

6. In a telephone system, a pair of lines joined by a voice current repeater, whereby weak talking currents may be received from one of said lines and repeated in amplified form to the other line, switching devices for connecting said repeater to repeat to either of said lines, a sensitive relay for controlling said switching device, means for bringing said relay under the control of either line, another sensitive relay for rendering said first sensitive relay ineffective, said first relay operated by either weak or amplified currents, and said other relay operated only by amplified currents.

7. In a telephone system, a pair of lines joined by a voice current repeater comprising a receiving and a sending device, means for maintaining'said sending device always 'in connection with only one of said lines, a

switching device for connecting said sending device to the other line, means for transmitting weak currents from either line to be repeated in amplified form by said repeater, said switching device adapted to be operated by current from either line, and means forrendering said switching device 'accessibleonly to current from the line to which the sending device is connected.

8. In a telephone system, a pair of lines joined'by a voice current repeater comprising a receiving and a sending device, means for maintaining said sending device always in connection with only one of said lines, a

switching device 'for' connecting said send- ARTHUR BEssEY SMITH. 

